Electrical control device



Nov. 27, 1928. y 1,693,313

E. J. MURPHY ELECTRICAL CONTROI; DEVICE original Fileduuly 9, 1924 I 2 sheets-sneer 1 Hts Attorney.

Nov. 27, 19278. 1,693,313

E. J. MIJRPHY l ELECTRICAL I CONTROL DEVICE original Filed July 9. 1924 2 sheets-sheet 2 Inventor: Edv/Ln J. Murphy.

Hts Attorney.

Patented Nov. 27, 1928.

UNITED STATES 1,699,319 PATENT OFFICE.

EDWIN J. MURPHY, OF SCEENECTADY, NEW YORK, ASS`IGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTRICAL CONTROL DEVICE.

`Original application iled July 9, 1924, -Serial No. 725,077. Divided and this application led February 9,

' 1927. Serial No 167.041.

My invention relates to electrical .control devices and has for its object the provision of simple and reliable means for controlling an and claimed in U. S. Patent No. 1,559,525 to Edwin J. Murphy and Leonard P. Hutt.

,This application is a division of my copending application Serial No. 725,077, filed July 9, 1924. f

In carrying out my invention in one form I provide a contact control device which is operatively connected to a reproducer of angular motion by means of electromagnetic connection Which permits any amount of inl dependent rotation of the reproducer with practically no restraint, but causes the contact device' to reverse the motor every hal revolution of such independent rotation. As a result of this action, the motor is controlled to drive the driven object by the shortest path into angular agreement of the controlling object.

For a more complete understanding of my invention reference should be had to the accompanying drawing inwhich Fig. 1 shows in diagrammatic fashion a system for reproducing position embodyin Fig. 2 shows in diagrammatm fashion a modified form of my invention; Fig. 3 is an enlarged View in perspective of the control device for the motor; Fig. 4 is a plan view of the device shown in Fig. 3; while Fig.` 5 is a detail view partially in section.'

Referring to the drawing, I have shown my invention in one formas applied to the driving of a position indicator dial 1() so as to maintain it automatically in angular agreement ywith a remotely situated telescope or sightingjdevice 11. As shown, the dial 10 is -aodriven by two electric motors 12 and 13, the

.'motprs beingwgeared to a common driving shaft 14 which is connected through a'worm 15 and-wormwheel 16 to the driving shaft 17 of the dial. Itcontemplated that one of the my invention motors will be used to'drive the dial in one direction, while `the other Will be used to drive the dial in the opposite direction. A single motor with two separate armatures and a single field winding may be used i11- stead.

The motors 12 and 13 are controlled by means of contact devices 18 and 19 which are actuated by reproducers 20 and 21 of the angular motion of the telescope. `These reproducers or receiving. devices operate in different ratios with the telescope, the reproducer 20 moving at a suitable high speed ratio such s 72: 1, with relation to the telescope, and the reproducer 21 moving at a low speed 1:1 ratio with the telescope. The reproducers 2O and 21 are electrically connected to transmitting devices 22 and 23 respectively which are geared to the telescope in the same ratios in which the reproducers are to be driven such as 72:1 and 1 :1 respectively. As shown, the transmitters are connected so as `to be actuated in accordance with the angular motion of the telescope in a horizontal plane. The receivers and -transmitters 20 to 23 inclusive are of similar construction, each being provided -With a polycircuit armature winding and a single circuit field winding, these windings being relatively rotatable. Preferably, the polycircuit winding is on the stator element of the device, while the single circuit winding is on the rotor element. As shown, the transmtting devices 22 and 23 comprise three-circuit stator windings 24 and 25 and field windings 26 and 27 respectively. It will be understood that the reproducers 20 and- 21 are similar in construction, the stators 28 and 29 of the reproducers being provided with three-circuit armature windings, and the rotors 30 and 31 being provided with single circuit field windings. Like points of the armature windings of the transmitter 22 and reproducer 20y are connected together by means of conductors 32, and likewise like points of the armature windings of the transmitter 23 and the reproducer 21 are connected together by conductors 33. The field windings of the transmitters and reproducers are connected to a suitable source of alternating current 33. Since the stators 28 and 29 of the reproducers are rotatably mount-ed, connec'# tions are made with the conductors 32 and 33 ,respectively by means of suitable conductor In the operation of systems of this character for transmitting angular motion, voltages are induced in the polycircuit stator windings of the transmitting and reproducing devices by the field windings on their respective rotors. lVhen the rotors of the connected transmitter and reproducer are in corresponding angular positions with relation to their stators, the voltages induced in the st-ator windings are equal and opposite and since like points of the windings are connected together, no current is set up in the armature windings. It the rotor of the transmitter is turned and held in a new position, the voltages then no longer counterba'lance, whereby equalizing currents are caused to flow in the armature windings, which currents result in a. torque applied to the rotor of the reproducer; This torque causes the rotor of the reproducer to turn to a position corresponding to the position of the transmitter rotor. Any movement applied to the transmitter is therefore reproduced with great accuracy bythe reproducer. Another char acteristic of systems of this character is that the reproducers turn to angular agreement by the shortest path. That is to say, if the reproducer rotor lags more than 180 its torque will be reversed and bein a direction to cause it to continue thelag and turn into angular agreement by completing a revolution of lag.

Secured to the driving shafts 40 and 41 of the reproducers and forming parts of the contact devices 18 and 19 are cylindrically shaped members 42 and 42*1 which carry pole pieces for magnet coils 43 and 43a. These members are rotated by the reproducers and by means of this rotation actuate pivoted contact arms 44 and 44u whereby the motors 12 and 13 are controlled.

Since the contact devices 18 and 19 are similar in construction only, one contact device 18 will be described in detail. Referring to Figs. 3, 4 and 5, the cylindrical member 42 comprises a cylindrical cup shaped member 45 made of a metal having a low magnetic permeability, such as aluminum. This memer is adjustably secured to the driving shaft 40 of the reproducer. On its periphery are two substantially semi-circular strips 45a and 45h. which are secured diametrically opposite each other on opposite ends of the member 45, that is, spaced along the axis of shaft 40. These strips are made of a metal having a high magnetic permeability, such as iron. Two adjacent ends of the strips are connected by a short inclined section 46, made of a similar material. 'This section preferably makes obtuse angles with reference to the strips 45a and 45b and has a narrow outer edge 46a. The opposite ends 47 and 48 of the strips are spaced apart and terminate in a plane passing through the axis of the member 45. The strips 45", 45b and section 46 form an armature or pole piece, which it will be observed is substantially an open ring having its ends spaced apart in an axial direction.

The coil 43 is mounted on a suitable support 49 consisting of two uprights 50 and 51 between which the coil is secured. At the sides of the coil are members 52 and 53 made of magnet core iron, the outer ends of which span the face of the cylindrical member 42 and are close to the strips 4521 and 45". As shown, the axis of the coil 43 is at right angles to the shaft 40.

A pivotally mounted member 55 of magnet core iron forming an armature pole piece,

passes through the coil 43 and on its end is provided with an inclined ridge 56, forming a pole face, which has approximately the same width as the outer edge 46a of thesection 46. Its inclination is such that it is in alinement with section 46 when section 46 is opposite it. This member 55 is pivotally mounted on the uprights 50 and 51. As shown, it has its pivoted end secured to a substantially disc shaped block 57 of insulating material to which is secured a cross bar 58'made of magnet core iron having on its ends ball bearing receptacles 59 and 60. EX- tending into the bearing receptacles are threaded pins 61, only one of which is shown, which are adj ustably secured on the uprights 5() and 51, supporting ball-bearings 61a being provided between the pins and the sides of the receptacles. Secured to the opposite side of the disc block 57 is the contact arm 44 whichy is provided with two resilient strips 62 and 62a. The contact arm 44 and the member 55 are in alinement and move as one part about the pivot axis formed by pins 61.

I-t will thus be observed that the coil 43 1s rovided with a magnetic circuit having three egs, the two outer legs 52 and 53 and the central leg 55. These legs are electromagnetically connected at their inner ends through the cross bar 58 and at rtheir outer ends through one or both of the strips 45l and 45" and section 46. The inner ends of legs 52 and 53 are concave to conform with the curvature of the bearing receptacles and are positioned near the bearing receptacles so as to leave but short air gaps 63. In order to prevent thel magnetic flux from passing through the bearing balls 61a and magnetizing them, the uprights 50 and 51 are made of a metal having a low magnetic permeability such as aluminum or bronze.

When the member 42 is rotated with the coil 43 energized, it will be observed that the pivoted member 55 will be swung downward as viewed in Figs. 3, 4 and 5, when strip 45hv them the contact arm is swung slowly from one contact to the other, and when section 46 stands exactly opposite pole face 56 the contact rarm is held in mid position. On the other hand, when the pole face 56 passes the ends 47 and 48 it is snapped quickly from one position to the other and cannot come to rest between the contacts.

- For the purpose of adjustment the clamping nut 65a may be loosened and the member 42 turned on shaft 40. -For small adjustments the bracket 49 may be turned about the shaft 40. As shown, it is provided with a circular projection 66 which tits into a groove in the support 67, the bracket being clamped to the support 67 by `bolts 68 extending through slots 69.

Referring again to Fig. 1, the servo motors 12 and 13 are preferably of a direct current shunt type and have their fields 70 and 71 permanently connected to a suitable source of supply 72. The circuits ofthe armatures 73 and 74 are controlled bythe contact devices 18 and 19. One terminal of armature 7 3 is connected through a conductor 75 to the contact 65 of device 18 and one/'contact 80 of device 19, while one terminal of armature 74 is connected through a conductorr7 6 to contactv 64 and the other contact 77 of device 19. The other two terminals of the armatures are connected together and through a conductor 78 to one side 72a of thevsup'ply source 72. As shown the magnet coils 43 and 43a are connected in series across the supply mains 72al and 72b. Thecontactv arm 44 of device 18 is connected through conductor 82, a switch 83, a resistance 84, and a conductor to supply main 72b, and contact arm 44a of device 19 is connected through a conductor 86 operating coil 87 of switch 83, resistance 88 and conductor 85 to sup ly main 72". The switch 83 is biased to closed position by means of the weight of its armature 83a.

The stators 28 and 29, as previously indicated, are rotatably mounted. The stator 28 is connected through gearing 90 to driving shaft 14, and the stator 29- is connected through gearing 91 to driving shaft 14. The various driving connections are so arranged that the gear ratio between the stators 28 and 29 is the same as the operating ratio between the rotors 30 and 31, and the gear ratio between stator 28 and the dial 10 is the same as f the operating ratio between the rotor 30 and eration of my invention is as follows: When the telescope is moved to a new bearing, the rotors 30 and 3l will reproduce this movement in their respective ratios whereby the contact arms 44 and 44l will be actuated. Assume, for example, that the telescope is rotated quickly through a considerable angle in such direction that Contact arm 44 is thrown into engagement with contact 64 and contact arm 44 into engagement with contact 77. In such case a circuit will be established from supply main ,72a through conductor 7 8, armature 7 4, conductor 76, the contact arm 44a, conductor 86,. coil 87, resistance 88, and conductor 85 to supply main 7 2b. This causes motor 13 to operate in such direction that the motor drives the indicator in a direction corresponding to the direction in `42a will be carried back with the rotors of the reproducers toward their previous angular positions until finally member 42El will move contact arm 44a out of engagement with contact 77 and break its control circuit. The control is immediately thereafter taken over by contact arm 44.

Motor 13, however, has given the dial a rough adjustment only under the control of the low speed or -coarse reproducer 2l. When the motor circuit is broken by contact arm 44a, coil 87 is deenergized whereby switch 83 closes in accordancewith its bias and the line reproducer 20 takes control to make the accurate adjustment of the dial 10. It is contemplated that the coarse reproducer4 21 due to its low speed ratio will give the dial only a -coarse adjustment which will be somewhat short of the correct adjustment. In practice it has been found that the motor does not stop when the control is transferred from the coarse to the fine reproducer. Under the assumed conditions, contact arm 44 will be in engagement with contact 64, whereby a circuit is established from supply main 72a through conductor 7 8, armature 74, contact arm 44, conductor 82, switch 83, resistance 84, and the conductor 85 to sup ly main 7 2*. The dial will be driven under tie control of the fine reproducer until they contact arm 44 is moved to open its circuit whereupon the motor comes to rest, the dial then being in angular agreement with the telescope.

When the ,telescope is rotated' in the opposite direction quickly through a considerable angle, contact arm 44a will be moved into engagement with contact 80, whereby a circuit is closed from supply main 72a through conductor 78, armature 73, conductor 75, contact arm 44, conductor 86, coil 8,7, resistance l'll) the contact 65 whereby a circuit is established from supply main 72a through conductor 78, armature 73, conductor 75, contact arm 44, conductor 82, switch 83, resistance 84 and conductor 85 to supply main 72b.

It will be observed that the members 42 and 42a are rotatable with little restraint and have unlimited freedom of rotation so that the reproducers 20 and 21 are free to turn immediately to positions of agreement with their transmitters. This latter feature is of particular importance when the reproducers are switched on the transmitters with the The resistance 84 which is included in the motor circuit when the fine reproducer has control may have a higher resistance than 88 wherebythe motor operates at a lower speed when the tine reproducer has control and may consequently be stopped more accurately.

Although both coarse and fine control systems have been shown, it is contemplated that.

one system only may be used. Ordinarily where one control system only is used, this system will be the coarse one. As has been previously indicated when both systems are used, each system operates independentl of the other in eii'ecting its particular adJustment of the dial.

While the coarse reproducer has control the motor may turn the fine reproducer, by means of the driving connect-ion with its stator, through a number of revolutions. For example, if the dial should lag 12 degrees, the motor in making the coarse adjustment will turn the tine reproducer somewhat less than 72 X 12 or 864 degrees which is 2 revolutions dial considerably out of angular agreement Wand 144 degrees. The electromagnetic drivwith the sighting device. It' the reproducers were prevented from snapping at once into angular agreement with their transmitters. excessive current would result in the transmitting and receiving instruments whereby\ they" would be overheated. Also the accuracy of any other receiving instruments which might be connected on the same circuit would be impaired. It will also be observed that the dial is always driven through the shortest angle into positional agreement. -`For example, in case the dial should lag more than 180 for any reason whatever, as might occur it the telescope were swung around with great rapidity, it will be observed that contact arm 44a will be reversed as the ends 47 and 48 o the strips pass by pole face 56 so that the dial will be driven into angular agreement by completing a. revolution of lag. When the reproducers are connected to the transmitters with the dial out of angular agreement with the telescope, the reproducers snap at once into angular agreement with their transmitters by the shortest route, since as has previously been observed this is a characteristic of transmitters and reproducers of the type shown, and the dial is driven in a corresponding direction and hence by the shortest path into angular agreement with the telescope. Under all normal conditions of operation, the reproducers follow their transmitters with ay slight lag, and when the transmitters are at rest the reproducers are in exact angular agreement therewith.

Ordinarily during the usual relatively slow training of the telescope, the dial is caused 'to follow the telescope under the control of Y the tine reproducer only, and itis only when Switching' 0I" high Speed training is done that Q the coal-'5e reproducer is called upon to take 94.5.5

control.

ing connection between the fine reproducer and its contact arm7 however, allows the fine reproducer to turn independently of the contact arm with practicall no coercion. During this movement it wil be observed that the contact arm operated by lthe fine reproducer will be reversed each half revolution. When the coarse reproducer finally gives up the control somewhat short of the correct position of the dial, the contact arm operated by the line reproducer will be in position to continue the movement of the dial and complete the aiocurate adjustment. The magnetic driving connection thus allows the com plete revolutions given the tine reproducer y the motor to be entirely neglected.

In the modified form shown in Fig. 2 a single driving motor 92 of the direct current shunt type is provided. This motor is controlled to rotate in both directions by means of the contact devices 18 and 19 through the interposition of a switch 93. The field 94 of the motor is permanently connected by means of conductors 95 to the supply mains 7 2al and 72b and the motor is controlled by controlling the energy supplied to its armature 96.

yThe relay 93 comprises two contact arms 97 and 98 which are electrically connected through conductors 99 and 100 to the terminals of the armature 96. These contact arms are forced apart by means of an ihsulated spring 101 into engagement with fixed contacts 102 and 103 respectively, and they are actuated into engagement with a central fixed contact 104 by means of operating coils 105 and 106. In order to prevent the engagement of both contact arms with the contact 104 at the same time, interlocking insulated projections 107 are provided on the contact arms.

When either one of the contact arms is in engagement vwith contact 104 the other is prevented from enga-gin by the engagement of the projections 107. he contacts 102 and103 are electrically connected together and to supply main 7 2b. Vhen the arms 97 and 98 are in engagement with contacts 102 and 103 it will be observed therefore, that the motor armature 96 is short circuited for dynamic braking, while the contact 104 is electrically connected to main 72a. AIncluded in the connection between contacts 102 and 103 and supply main 72b`is a resistance 108 which may be short-circuited by means of a switch arm 109. This switch arm is biased to open circuit position, by the weight of its operating armature and may be moved to closed circuit position to short-circuit the resistance by energizing an operating coil 110.

Contact. arm 44 is connected through a conductor 111 and a resistance 112 to supply main 72, and contact arm 44aL is connected by way of a conductor 113 through operating coil 110 to supply main- 722. The stationary contacts 64 and 77 are connected by way of a conductor 115 through operating coil 106 and conductor `116 to supply main 72b. Contacts 65 and 80 are connected by way of conductor 117 through operating coil 105 and conductor 116 to supply main 72".

- It will be understood that the driving connections between the shaft 14 of motor 92 and the dial 10 and the stators of the reproducers are the same as shown in Fig. 1. It will also be understood that the reproducers 20 and 21 are electrically connected to transmitting devices which are operated by movement of a controlling object substantially as shown in Fig. 1.

The operation of the modified form shown in Fig. 2 is the same as the operation of the form shown in Fig. 1 with the exception, however, that the contact devices 18 and 19 do not open and close the lcircuits of the driving motor, but instead control the relay 93 which in turn opens and closes the circuit of motor 02 for both directions of rotation. Assuming now an angular movement of the controlling object of such magnitude and in such direction that the contact arm 44a is moved into engagement with contact 80, a circuit is thereby closed from supply main 72a through coil 110, conductor 113, the contact arm 44, conductor 117, operating coil 105, and conductor 116 to supply main 7 2b. The energization of coil 105 throws contact arm 97 into engagement with contact 104 whereby a circuit for the motor is closed from supply main 72'v1 through this contact arm, conductor 99, the armature 96, conductor 100 and contact arm 98 to supply main 72b. The motor 92 is thus muc-cd to rotate in a direction to cause the dial 10 to follow the controlling object. By rear-on of the fact that coil 110 is energized resistance 108 is short circuit-ed during the operation of the motor under the control of Contact arm 44a so that the motor operates at high speed. After the dial 10 has been driven into angular agreement within the limit of the accuracy of the coarse reproducer, contact arm 44a will be moved away from contact 80 whereby coil 105 is deenergized and the control transferred to the fine reproducer. The contact arm 44 will then bein engagement with cont-act 65 whereby the control circuit is maintained from supply main 7 2a through resistance 112, conductor 111, the

contact arm, conductor 117, coil 105, and conductor 116 to supply main 72b. This maintains the energization of coil 105 keeping contact arm 97 in engagement with contact 104 whereby the motor continues to operate in the same direction as before to complete the adjustment of the dial, the motor circuit being broken by contact arm 97 when the dialhas been moved into accurate angular agreement by the movement of' Contact arm 44 to open the control circuit. Contact arm 97 then moves into engagement with contact 102 in accordance wth its bias whereby the motor is broughty to rest quickly by dynamic braking.

It will be observed that when the motor is operating under the control of the line reproducer, coil 110 is not energized and the resistance 108 is therefore included in the armature circuit of the motor so that it operates at a slower speed and can consequently be stopped much quicker than would-be possible when` operating at high speed under the control of the coarse reproducer. This facilitates the stopping of the dial in accurate angular agreement with the controlling object.

If the telescope is moved in the opposite direction contact arm 44a will be moved into engagement with contact 77 whereby a circuit is closed from supply main 72*1 through coil 110, conductor 113, the contact arm, conductor 115, coil 106, and conductor 116 to supply main 72b. This energizes coil 106 which throws contact arm 98 into engagement with Contact 104 whereby a circuit is closed in the reverse directionfor the armature of the motor from supply main 72a through the contact arm 98, conductor 100, armature 96, conductor 99 and contact arm 97 to supply main 7 2b. The motor then operates under the control of the coarse reproducer for the coarse adjustment, the control being then turned over to the fine reproducer to complete the accurate adjustment of the dial. When the control circuit is broken by contact arm 44a as the coarse reproducer gives up the control, contact arm 44 will be in engagement with contact 64 whereby the control circuit is maintained from supply main 72a through resistance 112, conductor 111, contact arm 44, conductor 115, coil 106, and conductor 116 to supply main 72". The motor then operates under the control of the fine reproducer un. til the dial has been moved accurately into angular agreement with the telescope when Yembodied in concrete form and as operating in a specific manner in accordance with the provisions of thepatent statutes, it should be l understood that I do not limit my invention thereto, since various modifications thereof will suggest themselves to those skilled in the art without departing from the spiritiof my invention, the scope of which is set forth in the annexed claims.

What I claim as new and desire to secure by Letters Patent of the United States, is,

1. A control device comprising a rotatable A magnet pole piece provided with axially displaced portions, and a movable magnet pole piece cooperating with said axially displaced portions as said first pole piece is rotated so as to be moved thereby from one position to another.

2. A control device comprising a rotatable magnet pole piece provided with axially displaced portions, and a movable magnet pole piece cooperating with said rotatable pole piece and moved thereby by magnetic attraction from one position to another each half revolution of said rotatable pole piece.

3. A control device comprising a. rotatable open ring magnet pole piece having its ends axially displaced, and a second magnet pole piece actuated by magnetic attraction from one position to another upon rotation of said first pole pieces.

4. A control device comprising an open ring magnet pole piece having its ends axially displaced, a rotatable support for said ring, and a second magnet pole piece pivoted about an axis perpendicular to the axis of said su port so as to be actuated by magnetic attraction from one position to another upon rotation of said ring.

.5. An open Vrin having its ends axially displaced, a rotata le support therefor, a metallic contact arm having one end adjacent said ring, a pivot for said contact arm at right angles to the axis of said ring, and a ma et coil provided with a magnetic circuit inc uding said ring and said contact arm Awhereby sald contact arm is moved about its pivot upon rotation of said ring.

netic circuit of said coil, and a pivoted memv ber coo rating with said rotatable member swung y magnetic attraction to one or another of two extreme ositions by one or the other of said axially isplaced portions and to an intermediate position by sai-d1 inclined portion.

7. A control device comprising a magnet coil, a rotatable member provided with two axially displaced substantially semicircular portions connected by an axially and circumferentiall extending central portion, said portions orming part of the magnetic circuit of said coil, and a pivoted member having its free end! cooperating with said rotatable member and swung by magnetic attraction to one or another of two extremepositions by said semicircular portions and to an intermediate position by said central portion.

8. A control device comprising a magnet coil, a rotatable support, an open ring pole piece mounted on said support with its axis coincident with the axis of rotation of said support, said ring forming part of the magnetic circuit of said coil and including two substantially semicircular portions displaced axially and an axially inclined portion joining said semicircular portions, a contact member also included in the magnetic circuit, a pivot support for said contact arm having its axis perpendicular to the axis of said rotatable support, said contact member having one end' cooperating with said ring so as to be moved by magnetic attraction to one or another of two extreme positions by said semicircular portions and to an intermediate position by said central axially inclined portion.

In witness whereof, I have hereunto set my hand. this 8th day of February, 1927.

EDWIN J. MURPHY. 

